Laser beam adjustment

ABSTRACT

An attachment for a hand held laser directed temperature measurement device includes a radiometer for invisible radiation detection and a laser beam generator for projection of visible laser light onto a target surface to identify a target area of measurement and includes a movable laser beam modifying carrier, such as a diffraction beam splitter, to display a selectable light pattern on the measurement target area.

This application is a Continuation-in-part of co-pending U.S. patentapplications: Ser. No. 09/605,329 filed Jun. 27, 2000, which claimspriority based upon Application No. 60/142,070 filed Jul. 2, 1999 andupon Application No. 60/147,021 filed Aug. 3, 1999 and upon ApplicationNo. 60/154,591 filed Sep. 17, 1999 and upon Application No. 60/185,385filed Feb. 28, 2000 and upon Application No. 60/198,384 filed Apr. 19,2000.

Ser. No. 09/605,330 filed Jun. 27, 2000, which claims priority basedupon Application No. 60/142,070 Jul. 2, 1999 and upon Application No.60/147,021 filed Aug. 3, 1999 and upon Application No. 60/154,591 filedSep. 17, 1999 and upon Application No. 60/185,385 filed Feb. 28, 2000and upon Application No. 60/198,384 filed Apr. 19, 2000.

This application claims priority from:

Serial No. 60/154,591 filed Sep. 17, 1999

Serial No. 60/185,385 filed Feb. 28, 2000

Serial No. 60/187,400 filed Mar. 7, 2000

Serial No. 60/198,384 filed Apr. 19, 2000

Serial No. 09/605,330 filed Jun. 27, 2000.

FIELD OF THE INVENTION

The present invention relates generally to the projection of laser beamsfor the directional aiming of apparatus such as radiometer instruments,which may be used for ascertaining the temperature of a surface usinginfra-red measurement techniques, and more particularly to suchapparatus which utilises a laser sighting device arranged to project oneor more laser sighting beams onto a target for identifying on thesurface of the target an energy zone thereof, the temperature of whichis to be measured.

It is useful, in the operation of such laser beam projection apparatus,to have the facility to change the number and/or configuration of beamswhich are issued from the laser beam projector.

By way of example, in a first case it may be desirable to have a singlebeam which is axial and which gives rise to a single central illuminatedspot on the target area to be investigated. In a second case it may bedesirable to have a plurality of laser beams which produce illuminatedspots on, for example, the periphery of a target area of a surface to beinvestigated. The selected production of a single spot, by a singlelaser beam, and of a plurality of spots by a plurality of laser beams,is conveniently arranged by providing a beam splitter, which may be forexample a diffraction lens or grid, which can be brought into and out ofoperation with respect to a single laser beam produced by the beamgenerator.

When a single laser beam is divided, by the beam splitter, into aplurality of beams, there is a corresponding proportional lowering ofthe strength of each of the plurality of beams, as compared with that ofthe single central beam. According to the degree of sub-division of thesingle beam, the strength of each of the plurality of beams may thenbecome too low to be of practical use, i.e. the illumination provided byeach of them on the surface of the target may be too weak to seeclearly, especially in bright ambient light, or at a relatively longdistance which may be essential in the investigation of a target surfacewhich is at a very high temperature.

It is not possible to overcome this factor of change of intensity, asbetween the single beam and the plurality of beams by merely increasingproportionately the power of the single beam when it is to besubdivided, because there are legal and practical restrictions on theuse of laser beams because of the possible danger to the user, e.g. thedamaging of eyesight. A requirement currently in force for a Class IIIALaser Diode is that the maximum output be less than 5 milliwatts.

It is known in practice in the art to utilise hand-held instruments,such as radiometers, which incorporate a laser beam generator for aiminga beam, or beams, at a target area, and a heat-sensitive device formeasuring the radiation which is emitted by the targeted area of aheated surface. Unless provision can be made for changing of thestrength of the laser beam, there is always a limitation of (a) thenumber of beams which can usefully be obtained from splitting of asingle beam, and (b) the effectiveness of the instrument, used with adistant target, because of the resultant relatively lowered illuminatingpower of each of the beams which is split from the original single beam.

OBJECTS OF THE INVENTION

It is a first object of the invention to provide an improvement, tolaser beam projection instruments having provision for projecting asingle, e.g. axial, beam and for dividing that single beam into aplurality of beams, by which the relative power of the single beam, andof the plurality of beams, can be varied so that the power of themultiple beams can be increased while still remaining within acceptablelimits.

It is a second object of the invention to provide an improvement, inlaser beam projection instruments, whereby the power of the single beamis variable at its stage of generation such that its power may be at anacceptable level while the single beam is being used, and may beincreased when a plurality of beams are produced, to enhance the utilityof the instrument at a distance from a target, while neverthelesskeeping the power of the plural beams at acceptable level.

It is a third object of the invention to provide an improvement, inlaser beam projection instruments, whereby the power of the single beamis made initially substantially higher than would be safe if used alongso as, when it is sub-divided into a plurality of beams, to permit thatplurality of beams each to have a usefully enhanced power, and wherebythe power of the single beam is reduced by attenuation, when used as asingle beam, so as to remain within acceptable limits.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and still other objects and advantages of the presentinvention will be apparent from the detailed explanation of thepreferred embodiments of the invention in connection with theaccompanying drawings, wherein:

FIG. 1 is a side elevation of a representative pistol-type radiometerinstrument shown in its condition of operation in which a single axiallaser beam is produced;

FIG. 2 is a side elevation of the radiometer instrument shown in itscondition of operation in which the single laser beam has been dividedinto a plurality of beams;

FIG. 3 is a side elevation of the radiometer instrument shown with ademountable attachment at its front end serving for optional productionof multiple beams from a normally single beam device;

FIG. 4 is an elevation, to an enlarged scale, of a first form ofattachment for the radiometer;

FIG. 5 is an elevation, to an enlarged scale, of a second form ofattachment for the radiometer.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1 of the drawings there is shown a radiometerinstrument 1 incorporating a laser beam production means which producesa single axial laser beam 2 which is directed at a target 3 and produceson the target an illuminated spot 4.

Referring to FIG. 2 of the drawings there is shown the same radiometerinstrument in an alternative manner of operation in which it produces aplurality of beams 2A which produce on the target a plurality of spots4A arranged in a circle to define an area 5.

Referring to FIG. 3 of the drawings there is shown a further embodiment6 of radiometer instrument which has at its front end a demountableattachment 6A which is adjustable, in the manner described below withreference to FIGS. 4 and 5, to produce selectively a single axial laserbeam and a plurality of spaced laser beams for defining an area of atarget;

Referring to FIG. 4 of the drawings, the attachment in a preferredembodiment of the best known mode incorporates a slide 7 which has in ita first opening 8 containing an attenuator device, and a second opening9 containing a beam splitter lens. When the slide is in its lowermostposition, on the front of the instrument, the attenuator in opening 8 ispresented in front of the laser beam source and reduces the strength ofthe single axial laser beam produced. When the slide is in its uppermostposition, the beam splitter in opening 9 is presented in front of thelaser beam source, and a plurality of beams (2A in FIG. 2) are produced.To retain the slide in position on the instrument, there is provided aslideway 10, for mounting on the radiometer instrument, having undercutlateral arms 11, 11 in which the slide can move vertically, and upperand lower stops 12 and 13 limiting the up and down movement of theslide.

Referring to FIG. 5 of the drawings, a slide 14 for mounting on thefront of the instrument has a plain opening 15 at its upper part, and abeam splitter lens 16 at its lower part. The slide 14 is movablevertically within limits, in a slideway, similar to that shown in FIG. 4for mounting on the radiometer instrument. On one side of the slide 14there is mounted a lug 17 which is positioned to engage which a switchart 18 on the instrument. The switch is incorporated in the powercircuitry of the laser in the radiometer 6 (FIG. 3) and according to theraised or lowered position of the switch arm 18, as the case may, thelaser is operated at full power or lowered power. When the slide 14 isin lowered position, and the plain hole opening 15 is presented in frontof the laser generator, the power of the laser is at a reduced scalewhich is safe and acceptable in use. When the slide 14 is in raisedposition, and the beam splitter is presented in front of the lasergenerator of the radiometer 6, the power of the laser is at an increasedscale so that the plurality of beams produced by the splitter can eachhave adequate increased power for acceptable visibility on the target.

The attachment may serve as an “add on” item which can be used forupgrading of existing laser radiometers and like instruments in which awide differentiation between the power of the single beam, and of theplurality of beams, would otherwise be detrimental. Some existingradiometers may incorporate means to vary the laser brightness, but withthe present invention there is the assurance that the brightness will beautomatically maintained at a preferred level within safety limits.

In an apparatus where a single centering beam is then switched to becometwelve area-defining beams, the change of intensity of eacharea-defining beam could be upgraded by a factor of twelve. A similardegree of down-grading of power would occur when the area-defining beamsare switched back to provide a single centering beam. Thus, although thepower utilised at the target in providing the area defining beams isperhaps twelve times that permitted for a single beam, there isnevertheless no risk of exposure to a higher power factor.

Another way in which the power used in each beam, and particularly inthe greater number of beams, can vary is to pulse the laser so as tohave periods of being “on” and “off”, or of lower average power andhigher average power, alternatively, with the result that a higher powerlaser can be used in a unit having average optical power output.

Change of the power utilised, from and into the respective factor, isobtained in a further embodiment of the invention by the use ofattenuator means.

By way of example such an attenuator, in one embodiment, is a memberwhich is movable, say by sliding or twisting, by the operator or by amechanism controlled by the operator or set to operate automatically soas to present different configurations such as patterns, or obscured ornon-obscured areas, or areas having varied degrees of attenuation, inthe path of the or each beam.

In another embodiment, the attenuator, such as an adjustable iris, isarranged to vary the focus and brightness of an optical device throughwhich the beam or beams is or are passed. In an embodiment theattenuator is linked to the beam-changing means so that when the numberof subsidiary beams is increased, which would otherwise reduce theirindividual power proportionately, the power of the main beam, or beams,is increased proportionately. This may result in the original outputpower of the main beam or beams being greater than the safety limitsmentioned above but the visible output of the apparatus at the targetcan still remain within the safety limits. In a further embodiment, suchan attenuator is incorporated in, for example, a movable member such asa turret or slide linked to a manual change-over control of theapparatus, or actuated automatically and sequenced in synchronism withthe sequenced changing over of the single beam to multiple beamoperation. The laser light, in another embodiment, is passed through ashutter mechanism which is automatic or manual.

In further embodiments of the invention, the attenuator is a beamsplitting system which permits only a portion of a beam to betransmitted, or else is a beam-strength-reducing arrangement such as apartially opaque screen, or an opaque disk centered in the beam.

It is a property of the combination of the human eye and brain thatthere is retention of a latent image for a short period of time, withthe result that for example an illumination which is being pulsed “on”and “off” in sufficiently rapid succession, as in a movie film, mayappear to the observer to be a constant illumination. This permits, inaccordance with a further embodiment of the invention, the use of asingle aiming beam, or a small group of aiming beams, and also permits anumber of area defining beams to be used in a pulsed manner at a rategreater than the memory of the combination of eye and brain, whilstnevertheless giving to the observer an impression of continuousillumination of the target. In particular, where a plurality of separatebeams are disposed along a circle or other area-defining figure, inaccordance with a further embodiment of the invention they are caused tomove step-by-step, or in continuous motion, along the area-definingfigure, e.g. the perimeter thereof, whilst being pulsed simultaneouslyor sequentially “on” and “off” at a rate, so that to the observer thearea-defining figure remains constantly illuminated, as a result of thelatent image effect. In this embodiment of the invention, for example, alaser of higher power that is otherwise used in a single continuous,i.e. non-interrupted, beam can be pulsed so as to produce a plurality ofbeams, e.g. twelve beams each having a pulsing rate for one-twelfth thetime of a continuous beam. The viewer's eye retention will, in effect,cause the circle to appear as twelve brighter illuminated spots.

In accordance with further embodiments of the invention, the movement ofthe plurality of beams is obtained automatically, electronically ormechanically, or by manual actuation by the user of the apparatus, andthe pulsing simultaneously and/or sequentially “on” and “off”, i.e. thevariation of strength, is obtained by variation of power used togenerate the beam, or by variation of the proportion of the beamutilised, for example by beam-splitting mechanism such as amultiple-mirror system, or a masking device with areas of differentmasking capability.

In a further embodiment of the invention, the beam splitter is arrangedto provide laser beam spots not only at the periphery of the targetarea, but also within the target area, including at the center thereof.

In a still further embodiment, the beam splitter is arranged to providedots, or other illuminated areas, in shapes other than a circle, and forexample in the form of a cross.

In accordance with still further improvements of the invention, meansprovided for the front end of a laser beam generating instrument, forexample on a pyrometer, for varying the nature of the beam emitted, aremade as an attachment in the form of a separate entity which is mountedremovably on the instrument, so as for example to be attachable anddetachable, for example utilising a self-tapping thread, as and whendesired, and so that attachments with different beam-varying propertiesmay be utilised as required. The attachments may conveniently haverelatively movable portions, for example in the form of a slideway, formounting on the instrument, and a slide movable in the slideway intorespective positions in which different forms or degrees of modificationof the laser beam are obtained. By way of example, such a movableportion may have positions in which it presents respectively a simpleopening or a beam splitter in the path of the laser beam, or again inwhich it presents a beam attenuator and a beam splitter in the path ofthe beam. In a further feature, the movable portion of the attachmentmay serve to actuate switching means, on the instrument, arranged tovary the strength of the laser beam appropriately.

In a further embodiment, the attachment provides selective productionof, for example, a single central beam of relatively higher power, foraiming at a target to permit accurate sighting on a selected area of thetarget, combined with a plurality of other or split beams directed atthe target for outlining an area thereof, or for producing a pattern ofspots on the target. In a further form, the plurality of beams may beshifted from time to time, say in a circle, so as more clearly tooutline a selected area of the target. In yet another form, theattachment provides projection of split beams which strike the target asa closed loop figure, such as a circle. In yet another arrangement, theattachment is constructed to divert a single laser beam to strikesuccessive plural points on a target so as effectively to outline anarea thereof, and preferably with a rapidity sufficient to result inpersistence of vision giving the impression of a full continuousillumination of the line of successive points.

I claim:
 1. In a hand held temperature measurement instrument having (a)a body structure and (b) a visible laser aiming beam directed from saidinstrument along a path to form a display of visible light on a targetsurface area and (c) a radiometer directed by said beam at said area fordetection of invisible heat radiation from said area, the improvementcomprising the combination of said radiometer and a laser beam modifyingdiffraction device, mounted on the body structure of said instrument,which is switchable into and out of a plurality of selectable controlpositions which present said device alternately in the path and out ofthe path of said laser beam and thus modify the display of visibleaiming light on said area.
 2. An attachment, as claimed in claim 1,wherein the carrier is slidable, with respect to the body structure, formovement into and out of said laser beam path.
 3. An attachment, asclaimed in claim 1, wherein the laser beam modifying means of saidcarrier include a laser beam brightness attenuator.
 4. An attachment, asclaimed in claim 1, wherein the laser beam modifying means of saidcarrier include a laser beam splitter.
 5. An attachment, as claimed inclaim 4, wherein said laser beam splitter is a diffraction lens.
 6. Thecombination of claim 1 wherein said carrier has a first positionrelative to the body structure in which it is traversed by a singlelaser beam produced by the instrument, and a second position relative tothe body structure in which said single laser beam is divided intoplural beams, and wherein the power of the single laser beam isincreased when said carrier is in its second position relative to thebody structure.
 7. The combination of claim 1 wherein said carrier has afirst position relative to the body structure in which it is traversedby a single laser beam produced by the instrument, and a second positionrelative to the body structure in which said single laser beam isdivided into plural beams, and wherein means are provided to attenuatethe power of said single laser beam in the first position of thecarrier.
 8. A laser beam sighting device integral with a handheldmeasuring or treatment instrument comprising (a) a laser beam generator,means projecting visible laser light onto a target surface, and forproducing a visible targeting light display on said target surfaceselectable alternately in time between at least one relatively brightercentral primary beam and a larger number of secondary dimmer light spotsfrom mutually divergent sub-beams, derived from said primary beam by adiffraction beam splitter, and (b) a movable switch means for selectingpatterns of alternating primary and secondary beam displays projectedonto said surface.
 9. A laser beam sighting device, as claimed in claim8, wherein said beam splitter is movable into and out of a position inwhich said splitter is illuminated by said primary beam.
 10. A deviceaccording to claim 9 wherein said beam splitter is hingedly movablebetween a position of illumination by said primary laser beam and out ofa position of illumination by said primary laser beam.
 11. A deviceaccording to claim 9 wherein said beam splitter is movable on a pivot.12. A device according to claim 9 in which said beam splitter swivelsalong an arcuate track.
 13. A device according to claim 8 in which saidbeam splitter is slidably movable into and out of engagement with saidprimary laser beam.
 14. A device according to claim 9 in which said beamsplitter is rotatably movable into and out of engagement with saidprimary laser beam.
 15. A device according to claim 9 in which said beamsplitter is periodically movable into and out of engagement with saidprimary laser beam.
 16. A method of operating a laser beam sightingdevice which comprises steps of: (a) generating at least one primarylaser beam; (b) directing said at least one primary beam to display thelocation of an area on a target surface; (c) splitting said at least oneprimary beam into more than two secondary beams in a diffraction beamsplitter to identify a closed loop bounding area on said target surface;and (d) selectively changing between primary and secondary beam displayson said surface.